The present invention relates generally to an apparatus and method for compounding a reinforced thermoplastic material and forming parts therefrom in a continuous process and, in particular, to an apparatus and method for continuously compounding a thermoplastic glass fiber reinforced material, extruding the material as a continuous extrusion having a predetermined cross section, cutting preforms from the extrusion and forming parts from the preforms.
The process of forming a sheet of reinforced thermoplastic material, such as glass fiber reinforced polypropylene, is well known. For example, the U.S. Pat. No. 4,439,387 shows a method of manufacturing a composite reinforcing structure by extruding fluid thermoplastic resin through an elongated die simultaneously with introducing a plurality of continuous fiber reinforcing strands into the die.
The U.S. Pat. No. 4,925,719 shows a high strength reinforced composite having an outer polymeric skin chemically and mechanically bonded to an inner foam core by an interface of longitudinally continuous strands, transversely continuous and randomly arrayed transverse strands, and randomly inclined short strands having end portions embedded in both the skin and the core.
The U.S. Pat. No. 4,931,358 shows a semifinished material formed of a thermoplastic polymer and a needled textile fabric made up of at least two layers of oriented continuous filament yarn and at least one layer of unoriented fibers.
The U.S. Pat. No. 5,085,928 shows a fiber reinforced composite matrix that includes one or more layers of unidirectional fibers alternated with one or more layers of a porous fibrous material all embedded in a thermoplastic resin.
The U.S. Pat. No. 5,185,117 shows a multiple extruder for compounding thermoplastic resin and random discrete length reinforcing fibers. The fibers are introduced into the inlet end of a compounding extruder, thermoplastic resin material is directed into a resin extruder, and molten thermoplastic material from the resin extruder is fed into a second port in the compounding extruder downstream from the fiber inlet whereby a homogeneous mixture of thermoplastic material and reinforcing fibers is discharged from the compounding extruder. The discharged material can be shaped into a preform which can be sent directly to a molding machine.
Also well known is the process of forming continuous filament webs. The U.S. Pat. No. 4,910,064 shows a non-woven web formed of a plurality of substantially parallel continuous filaments stabilized by melt blown fibers to create a coherent web.
The U.S. Pat. No. 5,077,116 shows a forming fabric for a papermaking machine having a base fabric made of interwoven machine direction and cross machine direction yarns and a non-woven array of fibrous strands adhered to one surface of the base fabric.
The U.S. Pat. No. 5,118,550 shows a substrate having a nonwoven sheet of synthetic textile material formed of unidirectional continuous filaments and reinforcing threads extending parallel in the lengthwise direction bonded to the textile material.
The U.S. Pat. No. 5,128,198 shows a preimpregnated fibrous material formed of a plurality of substantially parallel reinforcing filaments in between which is dispersed a polymeric water-soluble binding agent, an aqueous medium and solid particles of thermoplastic polymer.
The U.S. Pat. No. 5,188,878 shows a flexible, unidirectional thin glass prepreg having glass fiber monofilaments formed by spreading glass rovings in a thin layer, impregnating a matrix resin between the monofilaments and partially curing the resin.